The Siemens 5SU1354-0LV20 is an FI/LS combination unit — an RCD (residual current device) and MCB (miniature circuit breaker) in a single 1+N-pole module.
The 30 mA IΔn is the standard sensitivity for personnel protection (shock hazard) in residential and commercial final circuits per IEC 60364. The D=70 mm width is a standard 4-module DIN-rail footprint, fitting a standard 4-MOD enclosure cutout.